Questions tagged [integer]

For challenges involving the manipulation of integers.

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7
votes
2answers
67 views

Minimal number of banknotes to pay a bill

Suppose denominations of banknotes follow the infinity Hyperinflation sequence: \$ $1, $2, $5, $10, $20, $50, $100, $200, $500, $1000, $2000, $5000, \cdots \$. How many banknotes are required, at ...
16
votes
5answers
657 views

Dominate a zero-sum game

Consider a zero-sum game with 2 contestants. Each round, each contestant chooses, independently of each other, one of \$n \ge 2\$ different choices. Depending on the two chosen choices, one player is ...
-1
votes
1answer
101 views

Print all digits of an integer [duplicate]

Challenge Given a positive integer, find the fastest way to iterate over its digits. Bytecode size doesn't matter as much as speed of execution. Examples For 6875, the program would output ...
17
votes
20answers
2k views

Fibonacci Encoding

Fibonacci coding is a universal code, which can encode positive integers of any size in an unambiguous stream of bits. To encode an integer \$ n \$: Find the largest Fibonacci number less than or ...
16
votes
2answers
230 views

Decompress an integer, Jelly style

Jelly has compressed string literals, using the “...» delimiters. The way these work is by interpreting the ... as a base-250 ...
20
votes
9answers
556 views

Zeroes at end of \$n!\$ in base \$m\$

Related: Zeroes at the end of a factorial Today, we are going to calculate how many zeroes are there at the end of \$n!\$ (the factorial of \$n\$) in base \$m\$. Or in other words: For given integers \...
11
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4answers
666 views

Golf this Thumb-2 Constant!

One thing that is constantly frustrating when golfing ARM Thumb-2 code is generating constants. Since Thumb only has 16-bit and 32-bit instructions, it is impossible to encode every immediate 32-bit ...
15
votes
8answers
720 views

Close(st) Binary Boxes

Challenge: Given a list of non-negative integers, determine by how much you should increase each item to create the closest binary box with the resulting integer-list. What is a binary box? A binary ...
14
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33answers
2k views

Implement a zipwith function

zipwith is a functional construct that takes three arguments: one binary function and two lists of the same length, and returns a single list where each element is ...
20
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36answers
2k views

Print a conversion table for (un)signed bytes

Your task: Print or return a conversion table with every byte from 00 to ff's value as an unsigned integer, to its value as a ...
22
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18answers
1k views

Interpret Interval Notation

Interval notation is a way to write complicated range bounds more conveniently and concisely than writing an inequality. The challenge, should you choose to accept it, is to write a program or ...
1
vote
1answer
143 views

Twist on words to numbers [closed]

The Goal The goal of this question is to put a twist on this question. Your answer should be able to convert an array of words associated with integers into those integers. As an extra challenge, ...
12
votes
7answers
634 views

Generalised Taxicab Numbers

\$\newcommand{T}[1]{\text{Ta}(#1)} \newcommand{Ta}[3]{\text{Ta}_{#2}^{#3}(#1)} \T n\$ is a function which returns the smallest positive integer which can be expressed as the sum of 2 positive integer ...
28
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28answers
2k views

Ken Iverson’s Favourite APL Expression?

Ken Iverson, 1920–2020 Let's implement his favourite expression: Given a row of Pascal's triangle, compute the next row. This can for example be computed by taking the input padded with a zero on the ...
29
votes
49answers
4k views

Multiply or Divide by n

Here's a simple challenge, so hopefully lots of languages will be able to participate. Given a positive integer \$n\$, output \$A076039(n)\$ from the OEIS. That is, start with \$a(1)=1\$. Then for \$n&...
33
votes
23answers
3k views

Narcissistic loop lengths

A narcissistic number is a natural number which is equal to the sum of its digits when each digit is taken to the power of the number digits. For example \$8208 = 8^4 + 2^4 + 0^4 + 8^4\$, so is ...
11
votes
14answers
861 views

Prefix divisibility

Inspiration Given a positive integer \$1 \le n \le 9\$, output all positive \$n\$-digit integers \$i\$ for which the following is true: Each digit from \$1\$ to \$n\$ appears exactly once in \$i\$. ...
25
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29answers
2k views

Not so triangular numbers

Let's consider the sequence \$S\$ consisting of one \$1\$ and one \$0\$, followed by two \$1\$'s and two \$0\$'s, and so on: $$1,0,1,1,0,0,1,1,1,0,0,0,1,1,1,1,0,0,0,0,...$$ (This is A118175: Binary ...
22
votes
17answers
2k views

A Portuguese sequence of integers

Context Consider the following sequence of integers: $$2, 10, 12, 16, 17, 18, 19, ...$$ Can you guess the next term? Well, it is \$200\$. What about the next? It is \$201\$... In case it hasn't become ...
14
votes
23answers
2k views

We're all unique in our own way

This is an answer-chaining challenge where every part of your answer should aim to be unique from every other answer. This question will work in the following way: I will post the first answer. The ...
20
votes
42answers
3k views

Converting Strings to Decimals (Gone Wrong)

What? Many programming languages, both practical and esoteric, have functions, methods, etc to convert a given string to a decimal number. This is how the process might work: For each character in ...
18
votes
13answers
1k views

Find all integer pairs that produce a given Loeschian number

Inspired by and drawns from Is this number Loeschian? A positive integer \$k\$ is a Loeschian number if \$k\$ can be expressed as \$i^2 + j^2 + i\times j\$ for \$i\$, \$j\$ integers. For example, ...
14
votes
4answers
446 views

Bad matrix multiplication that gives the right answer

Executive summary: Print NxN matrices \$A\$ and \$B\$ where \$ AB = 10A + B \$. Largest N wins! Details: Entrants in this challenge should choose an N. Submit a program that takes an input integer '...
11
votes
1answer
395 views

Amount Of Potential Keys That'll Fit The Lock

Introduction: You're a key maker, and want to access something from a safe that has a lock. Unfortunately, the key to that lock is lost, so you'll have to make a new one. You have access to a bunch of ...
25
votes
17answers
3k views

A long long time ago, in a galaxy … right here

Task Given a positive integer return the geologic era and period it was that many million years ago. Input/output The input is a string or integer; the output is a string. Eras and periods are ...
19
votes
16answers
2k views

Find the discrete logarithm

Task Write a program/function that when given 3 positive integers \$a, b\$ and \$m\$ as input outputs a positive integer \$x\$ such that \$a^x\equiv b\ (\text{mod}\ m)\$ or that no such \$x\$ exists. ...
5
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5answers
246 views

Divide into 2 isosceles triangles

Given the measures of two of the interior angles of a triangle (x and y; the other angle can be easily calculated with ...
21
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6answers
2k views

The matrix has U

Given a matrix of size at least 3×3 formed by positive integers, determine if it contains at least one "U" pattern, defined as ...
12
votes
3answers
727 views

Metagolf the OEIS

We've had Meta Regex Golf and Display OEIS Sequences. Now, it is time for Meta OEIS Golf. Challenge Given a sequence of integers, your program/function should output a program/function in the same ...
0
votes
2answers
190 views

Remove each integer from a string and multiply them all! [closed]

Goal: Get every integer from the string (not a number, but integer) Multiply them Output the result Input: 5 kilograms of food eaten, 10 liters of water drank, 20 plates dirty, 40 mugs dirty, and ...
22
votes
23answers
1k views

Complete a sequence using its distances

Given \$A = (a_1,\dots,a_k)\ k\ge2 \$ a sequence of positive integers, in which all elements are different. Starting from \$i=2\$, while \$a_i\in A:\$ (until the last element) If \$d=|a_i-a_{i-1}|\$ ...
19
votes
23answers
2k views

Zero the byte (eventually)

Given an infinite arithmetically-progressive¹ sequence, compute the minimum length of a prefix with a product divisible by 2^8. Sample cases & reference implementation Here is a reference ...
12
votes
10answers
2k views

Integers in cosine

Integers in cosine From trigonometry we know that \$\sin(a) =-\cos(a + \frac{(4*m + 1)\pi}{2})\$ where \$a\$ is an angle and \$m\in\mathbb{Z}\$ (integer). The task For an input of a positive integer \$...
9
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8answers
654 views

Perfect scores in Martian rules football

Story Martians have been observing Aussie rules football matches from space with great curiosity. Having totally fallen in love with the game, they have been inspired to start their very own football ...
20
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14answers
2k views

Donation arms race

The barfoos, a hypothetical alien species, go about charity in an interesting way. Every morning, barfoo Specialists come up with an ordered list of causes to donate to, and for each cause they ...
17
votes
9answers
2k views

Missile-mounted cameras

You are employed as Administrator in charge of Road Maintenance and Planning. The intelligence division of the Agency for Road Maintenance and Planning has come up with a brilliant and not at all ...
16
votes
42answers
2k views

Generate list of numbers and their negative counterparts

A recent SO question asks for a convenient one-liner to generate a list of numbers and their negative counterparts in Python. Given two integers \$1≤a≤b\$, generate all the integers \$x\$ such that \$...
18
votes
5answers
951 views

Generate Green Spray Paint Patterns

This challenge is about creating these neat "green spray paint" patterns: (more pictures below) Loosely explained, they are generated by starting with a black image and a point in the center. ...
51
votes
31answers
7k views

Conway's Monster

This challenge is in honor of mathematician John Conway who passed away April 11, 2020 due to COVID-19. He was famous for coming up with the Game of Life cellular automaton and many other mathematical ...
17
votes
3answers
683 views

Make a rectangle from a collection of (sliced) squares

Inspired by Make a Rectangle from a Triangle. Task There is a famous formula on the sum of first \$n\$ squares: $$ 1^2 + 2^2 + \dots + n^2 = \frac{n(n+1)(2n+1)}{6} $$ It is known that this number ...
22
votes
17answers
3k views

Make a Rectangle from a Triangle

You can depict a triangular number, T(N), by writing one 1 on a line, then two 2's on the line below, then three 3's on the line below that, and so on until N N's. You end up with a triangle of T(N) ...
24
votes
9answers
859 views

Maintain diagonal symmetry when placing N items on a square grid

Write a program that takes in two non-negative integers S and N in that order. S represents the side length of a square grid of . characters. N represents the ...
15
votes
14answers
1k views

Generating generating expressions for sequences

(yes, "generating generating" in the title is correct :) ) Context In middle (?) school we are taught about sequences and, in particular, we are taught about linear sequences where the ...
25
votes
20answers
2k views

Four distinct 8-bit integers

Submit a well-formed program or function with usual I/O rules which satisfy the input, output, and algorithm conditions below. Shortest submission (in bytes) wins. As always, standard loopholes are ...
12
votes
4answers
458 views

Solving the water bucket riddle!

Context The water buckets riddle or the water jugs riddle is a simple riddle that can be enunciated in a rather general form as: Given \$n > 0\$ positive integers \$a_1, a_2, \cdots, a_n\$ ...
19
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24answers
2k views

A bit of a digital XOR

Here are the first 100 numbers of a sequence: ...
17
votes
20answers
2k views

All aboard the factorial train

The system Assume the Earth is flat and that it extends infinitely in all directions. Now assume we have one infinitely long train railway and n trains in that ...
29
votes
46answers
5k views

How many petals around the rose

How many petals around the rose How many petals around the rose is a dice game you can play with your friends. Similar to "can I join the music box", there is a person that knows how the ...
15
votes
23answers
2k views

Summing a sub-square of a quarter of an infinite chessboard

Description of the problem Imagine a quarter of an infinite chessboard, as in a square grid, extending up and right, so that you can see the lower left corner. Place a 0 in there. Now for every other ...
9
votes
5answers
504 views

Computing a specific coefficient in a quotient of polynomials

Context After "Computing a specific coefficient in a product of polynomials", asking you to compute a specific coefficient of polynomial multiplication, I wish to create a "mirror" challenge, asking ...

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